"I'm here for the read-through of episodes seven and eight," Redgrave said on a video released by the BBC.

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"I'm here in Cardiff and really, really happy and thrilled because Kate Stewart is back."

Redgrave was already announced to return in series nine's opening double-header of 'The Magician's Apprentice' and 'The Witch's Familiar', and has now been confirmed for episodes seven and eight of the ninth series.